Climate Change and the Future Character of War

Introduction

The results of humanity’s addition of greenhouse gases to the atmosphere are now being felt. The atmospheric concentration of carbon dioxide, methane, nitrous oxide and other greenhouse gases has increased alarmingly since the Second World War, and as a consequence the earth is warming, and is doing so at an accelerating rate. Humanity’s modification of the atmosphere began in the 18^th century with the onset of industrialisation and the burning of fossil fuels. To date, international efforts to stop the emission of these gases have largely been unsuccessful, particularly in the critical high-emitting nations. For all of humanity, the consequences are now unavoidable; climate change has arrived.

Much has been written and reported about climate change, so its onset and effects should come as no surprise.^[1] The seas are rising, the ice is melting, storms are becoming more potent and the animals and plants that cannot adapt rapidly enough to new conditions are dying. What may come as a surprise to some, however, is that climate change also represents a major national threat to the security of Australia, as well as to that of other nations. In fact, it is arguable that climate change is the most serious threat the nation has ever faced.

Numerous senior military leaders are alive to the risk that climate change represents to their respective states. In Australia, General Angus Campbell, Chief of the Defence Force, has observed that ‘climate change and Australia’s national security are inextricably linked’.^[2] A former commander of what was previously known as the United States (US) Pacific Command, Admiral Samuel Locklear, has called climate change the biggest danger in his area of responsibility, a position he reiterated to the United States Senate Committee on Armed Services.^[3] In the United Kingdom, Rear Admiral Neil Morisetti has declared that no country can afford to ignore the risks to its security from a rising temperature.^[4] These positions are not unusual within the military community. Between 2017 and 2019, more than 35 senior US Department of Defense officials publicly voiced their concerns over the security implications of climate change.^[5] President Biden’s Secretary of Defense, Lloyd Austin, has continued the pattern by labelling climate change an ‘existential threat’.^[6] 

In the light of climate change, Australia’s military and political leaders, as well as its defence strategists and planners, must re-express and reprioritise how they identify, assess and ameliorate the nation’s security risks. The traditional approach is state focused and requires defence planners to assess the threat of a potential adversary state and, with government’s agreement, put into place appropriate defence policies that reduce the risk to an acceptable level. For example, in the early years of the 20^th century, Australian leaders identified Japan as the most likely threat to its territory and interests.^[7] The 2020 Defence Strategic Update makes it clear that today China occupies that space.^[8] The 2023 National Defence: Defence Strategic Review calls the US–China competition ‘the defining feature of our region and our time’, a conclusion that the 2024 National Defence Strategy shares.^[9]

As national security thinkers consider future threats, they must now move climate change to the fore, since the greatest and most likely risk warrants the most serious attention.^[10] To increase the focus on its danger, this article will first explain why climate change is a national security risk. It will then highlight the consequences for the Australian Defence Force (ADF) and the Australian nation of not addressing the risk. Lastly, it will provide recommendations for what the ADF and the Australian public must do if the nation is to prepare for war in the age of climate change.

Climate Change as a National Security Risk

According to the United Nations, the most useful way to describe climate change in security terms is as a ‘threat multiplier’.^[11] Climate change causes a worsening of existing conditions, fostering situations in which a state (or sub-state) is no longer able to meet the needs of its people. Under great stress, the people of a state will make decisions that affect the security of their own territory and that of the surrounding region, and possibly the world. For example, climate change affected states might decide to meet the needs of their people by recourse to war or by encouraging people to migrate in mass. The US think tank CNA contends that climate change will exacerbate existing stressors to the point at which they exceed the ability of many governments to manage.^[12] The most critical needs are, of course, food and water. Any shortage of these necessities is likely to increase the risk of unrest and destabilisation, which may ultimately lead to societal collapse. Such circumstances fuel a greater willingness among societies to resort to force to safeguard their needs.

For more than a decade, the United Nations and the US Department of Defense have highlighted the likelihood of a more violent future induced by the stressors of climate change. The 2014 report from the Intergovernmental Panel on Climate Change (IPCC) observed that ‘multiple lines of evidence relate climate variability to … conflict’.^[13] The most recent IPCC report identifies numerous irreversible and interconnected risks resulting from climate change that affect ‘ecosystems, biodiversity and human systems’^[14]. Moreover, the report’s authors expect climate change effects to interact, causing disruptions to human systems to cascade across regions.^[15] In a similar vein, an intelligence report produced by the US National Intelligence Council anticipated that climate change would have ‘significant direct and indirect social, economic, political, and security implications during the next 20 years’.^[16] An earlier US report was similarly frank in its conclusions. Its authors stated:

Many countries important to the United States are vulnerable to natural resource shocks that degrade economic development, frustrate attempts to democratize, raise the risk of regime-threatening instability, and aggravate regional tensions. Extreme weather events … will increasingly disrupt food and energy markets, exacerbating state weakness, forcing human migrations, and triggering riots, civil disobedience, and vandalism. Criminal or terrorist elements can exploit any of these weaknesses to conduct illicit activity and/or recruitment and training. Social disruptions are magnified in growing urban areas where information technology transmits grievances to larger … audiences and relatively small events can generate significant effects across regions or the world.^[17]

While much of the predicted instability and violence is likely to be internal to fragile states, it has the potential to trigger widespread and pervasive regional unrest and migration throughout affected regions, including those in which Australia has a significant national interest. Large parts of the world may even collapse into anarchy along tribal, clan, creed or geographical lines and become ungoverned spaces.^[18] As states collapse, Australia may have to contend with widespread regional disturbances and outright conflicts where the rule of law has ceased to exist. Of particular concern is the fact that humanity is only at the start of its climate change journey. If greenhouse gas emissions are not halted quickly, warming will reach more dangerous levels than already exist and will further reduce the availability of resources and the capacity of states to cope. 

Assessing the Risk

Prior to industrialisation the quantity of carbon dioxide in the atmosphere averaged less than 280 parts per million. As of April 2024, it had reached 426.57 parts per million. The concentration of other greenhouse gases has also risen; between 1990 and 2019 the Average Greenhouse Gas Index, which factors in all greenhouse gases, had increased by 45 per cent. As of 2023 the Average Greenhouse Gas Index had reached the carbon dioxide equivalent of 523 ppm.^[19] To date the global average temperature has risen by more than 1.2°C. A 1.2°C rise may sound trivial, but it represents a massive amount of heat added to the planet’s ecosystem. To put it in energy terms, for the oceans alone a 1.2°C temperature rise represents the addition of 217 zettajoules of energy to the earth system.^[20] Worryingly, it appears likely that humanity will be unable to meet the target of holding to preferably below 1.5°C of warming, which was set by the Paris Agreement of 2015.^[21] Warming of 2°C would be disastrous for many parts of the world, yet a rise by more than this is looking highly probable.

The evidence that climate change is occurring is all around us; observable changes in the environment have become commonplace. Perhaps the most visible evidence that the climate is changing is found in the cryosphere, the part of the planet’s surface that is covered by ice. Everywhere, the ice is retreating.^[22] Each year, on average, the Arctic Ocean ice recedes further, Antarctic ice shelves melt and crash into the sea and mountain glaciers are in retreat. On 14 August 2021 rain—not snow—fell on the highest point of Greenland’s vast ice sheet for the first time in its recorded history.^[23] More dramatically, in 2016 the surface of a lake in Alaska boiled with methane released by the warming of its previously frozen bottom.^[24] At the same time as the ice is melting, tropical reefs are dying due to the rising temperature of the water.^[25] Agriculture too is being affected. In South Australia’s Clare Valley, for example, the wine harvest now occurs a month earlier than previous practice because the grapes ripen sooner.^[26]

These visible signs of climate change are not isolated phenomena without significance for humanity. Rather, they are symptoms of a destabilising natural world, holding serious implications for humanity’s survival. A major 2019 report from the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) observed that nature is essential to human existence and quality of life.^[27] Humans like to think of themselves as somehow apart from or superior to the natural world, but the reality is that we are just another one of its elements and entirely dependent on it for our survival. The global ecosystem contributes critical services that humans exploit, including pollination of food crops, nutrient cycling, soil creation and the basic necessities of air and water. These ‘gifts’ form the bedrock upon which humanity has constructed its civilisation. Indeed, they feed the current global population of over 8 billion people, which will reach 9.7 billion by mid-century.^[28] The fact remains that civilisation’s sustainment and humanity’s survival require constant interaction with the natural world.

Humans meet their needs by integrating their production and distribution systems with the numerous services provided by nature. For example, farmers have learned how to exploit the soil, rain and nutrients to optimise their harvest; fishers have learned when and in what quantities a particular fish will be at a particular location, and graziers move their animals in line with the availability of grass and water. Those who grow our food maximise their yields by optimising their interaction with natural systems.^[29]Their success depends on a stable ecosystem that provides the inputs primary producers need on a regular and predictable basis. Unfortunately, the changes to the environment that climate change will cause create a less vibrant, predictable and useful ecosystem. A less reliable environment reduces the opportunity for human production systems to leverage natural ones, thereby leading to lower yields of food and other resources. 

Climate change places the human need to integrate with the natural world at risk because it adds instability to the environment on which humanity depends. Already, organisations have begun to make changes in risk profiles in order to account for the additional threat that climate change represents. For example, much higher insurance premiums are unavoidable for those whose homes are in danger from storms, floods, coastal inundation or fires, while municipalities are updating building codes to make structures more survivable. The Chief Risk Officer of Insurance Australia Group has called for improvements in the assessment of risk and has stated that otherwise the industry may not survive.^[30]

For most of the world’s population, particularly in less wealthy countries, the risks from climate change are existential. This is because there is a correlation between an unstable climate and human misery. According to Stephen Emmott, in his book on feeding a population of 10 billion (a figure which humanity will reach before the end of the century), the global food production system is dependent on a stable and favourable climate.^[31] If human systems are unable to interact efficiently with natural ones, the result will be a decline in production of the resources needed to support the global population. For example, as sea levels rise, salinity increases in hitherto fertile river deltas, such as the Mekong, reducing productivity.

The situation is particularly acute if resource shortages occur in countries that are already unable to produce enough food to meet their needs. Every state has a carrying limit—that is, the capacity of its land and seas to meet the needs of those who live there. If a society was unable to generate adequate resources in the past, a period of starvation and death ensued until population and carrying capacity were again in harmony. For much of human existence societies went through 'boom-and-bust cycles of rapid population growth and starvation’.^[32]

Today, the international food trading system acts as a safety valve, providing food to those states that cannot meet their own needs. However, this safety valve only exists if there is sufficient surplus in the international system. As climate change reduces global food yields, the strain on many countries will become extreme. The Syrian Civil War provides a case study on what happens when people are unable to obtain food. A drought, the most severe for which there were records, caused a multi-year crop failure which forced 1.5 million Syrians to abandon their farms. Yields of wheat fell 47 per cent and those of barley 67 per cent, and livestock populations plummeted. Farmers and their families migrated to the nation’s cities, and by 2010 internally displaced people made up 20 per cent of Syria’s urban population. At a meeting with a UN official the Syrian Minister of Agriculture warned that the economic and social fallout from the drought was ‘beyond our capacity as a country to deal with’.^[33] The Assad government failed to meet the needs of the displaced people, which directly contributed to the outbreak of the civil war. Facing starvation, desperate people make desperate decisions. As Syria shows, famine-induced instability may lead to challenges to central authority, the break-up of countries along ethnic or religious lines, inter- and intra-state war, and mass migration.^[34]

The ADF in an Age of Climate Change Wars

In this more tumultuous future, the ADF can expect to become involved in wars with greater frequency, if only as peacekeepers separating multiple adversaries. The ADF should also expect to take a larger role domestically as natural disasters become more severe and more common. When he was Chief of Army, General Angus Campbell, in an address to the Australian Strategic Policy Institute, described the future as a more disruptive age.^[35] What then can the ADF expect its future operations to look like? What will the character of war be when the ever-present feature of the age is climate change disruption, instability and conflict? 

On the tactical level, it is likely that little will be different from the present. Combatants will fight with what they have at hand, whether that is a machete, an improvised bomb, a tank or a drone. Tactics will be shaped as always by the interplay between technology, training, doctrine and national preference, set within a framework defined by the political aim. Some adjustments will be required, however. Personnel will have to be able to operate in temperatures that are higher than previously experienced, while platforms optimised for environmental conditions that no longer exist may have to be modified or scrapped. Diseases currently prevalent in the tropics will expand their ranges, necessitating greater investment in military medicine and prevention. Specialised health units, such as the Malarial Control Units that the Army once possessed, may need to be re-raised.^[36]

The underlying philosophy of war will also be unchanged. It will remain a deliberate decision made by a people to obtain something they want—food, land and safety—that they cannot obtain by other means. The non-aggressor in a war will have to make the same decision that it always has had to make—that is, to submit or resist. War will remain a contest between two or more states (or peoples). Climatic events will create a background of resource shortage and human strife in which deciding for war is increasingly seen as the best option. 

It is the social level of war where the important differences lie. For most people, particularly those in the West, war has become an optional affair waged to achieve limited goals. The great wars of the 20^th century are now a distant memory. All the veterans of the First World War are gone, and few from the Second World War remain. The horrors of the Thirty Years War of the 17^th century are only of interest to historians. For our generation, war’s role in shaping human events has taken a back seat to other drivers of social change, such as globalisation, instantaneous communications and ready access to infinite amounts of information via the internet. However, as societies come under strain from climate change and begin to unravel, war will resume its place as one of the great forces for human decision-making.

In response, the ADF will need to prepare for more frequent and larger deployments, even simultaneous ones, waged against people who believe war is the best, if not the only, means to solve an existential crisis. Because of their nature, these struggles are likely to lead to decisions that favour one participant over the other. For some displaced people, mass migration may be the only option. For others, losing will mean death. The fate of entire nations and peoples will again hang in the balance as has so often been the case in the past. War will resume its place as the great decider of which societies endure and which disappear. This is a more violent and decisive future, and one the ADF and Australian society have not experienced since the Second World War. It is also a kind of war that the ADF is not prepared for culturally, intellectually, socially or materially. 

Australia and the ADF will have to adapt if the nation is to meet the demands of operating in a more violent and decisive climate change era. The following considerations are particularly relevant in this regard:

• Wars of existence are about sovereignty—or more crudely survival. Those societies that are unable or unwilling to bear the price of survival will cease to exist. Not everyone will survive
• The ADF will need to get bigger, particularly the Army, and have a reserve that is more employable. The nation’s military forces will need greater depth to deploy larger forces on more frequent missions as well as to replace casualties.
• Unlike the optional wars that Australia has participated in since 1945, the coming wars will matter, for Australians as well as for others. Such wars absorb a greater share of the national estate both in people and wealth. For the government, the need to fund more frequent military operations will strain the budget, requiring a monetary reprioritisation. 
• Australia will likely not have the luxury of depending on a great power partner to do the heavy lifting or to provide the support and enablers that the ADF presently lacks in sufficient depth. Instead, Australia may have to pay for more self-reliance by providing for all the costs of sovereignty on its own.
• In wars of existence soldiers and civilians die, generally in large numbers. ADF personnel will need to be hardened to killing and to the loss of mates, while Australian civilians will need greater resiliency in the face of mass casualties.
• Wars of existence require the participation of the entire society. The Australian citizenry will no longer be able to contract out their military requirements to a professional organisation. This does not necessarily necessitate a return to conscription, but it will require greater emotional and financial involvement by the public in the nation’s wars.
• Wars of existence are financially expensive and wasteful. The funds allocated to security will need to consume a larger share of the nation’s wealth.
• ADF members will need to be accustomed to longer deployments, as will their partners and families. Wars of existence are likely to be prolonged.
• In wars of existence, moral values are challenged, particularly if the struggle is lengthy and costly. Australia may have to decide on how big a lifeboat it is willing to provide.
• In a world driven by climate change disruption, robust supply lines will likely not exist. The COVID-driven logistic crisis of 2021–2022 is a warning as to how vulnerable supply chains are when affected by a global disruption. Australia will again suffer from being a minor market at the far end of the supply chain. The current fleet of high-technology platforms may also prove problematic to sustain. A simplification of weaponry will be likely, while the nation will need to improve its sovereign industrial and social capability if it is to produce and sustain the depth of resources required.
• Climate change may create a two-tier world in which some countries maintain current levels of technology, while other areas are unable to sustain them. 

Like every country, Australia will be severely challenged by climate change and will not escape unscathed. Yet it is one of the countries better placed to manage a transition to what will be a different world. This is because Australia is an educated, wealthy and technologically advanced society with a cohesive population. Australia’s greatest advantage, however, is that it is one of few countries that exports more food calories than it consumes. In fact, Australia typically exports 70 per cent of its agricultural production.^[37] Therefore, if climate change leads to a reduction in global net food production, Australia has spare capacity to meet domestic requirements. Australia’s present overseas customers will bear the consequences of a lessening in food availability. Whether Australia will be able to meet the needs of its own population depends on the ferocity with which climate change disrupts the nation’s food production systems, the nation’s skill at adapting to a new situation, the policies the government implements, and the ADF’s ability to safeguard the nation’s resources from external threats.

Australia also has liabilities that will challenge its security in a climate-changed future, however. Perhaps the greatest of these is its culture of dependency. For its entire history, Australia has contracted out much of its sovereignty to a great power protector. The US has provided a credible strategic alliance that has guaranteed Australia’s future.^[38] This may no longer be an option in a world wracked by climate change. The US is likely to have too many worries closer to its homeland to be concerned about a distant friend. The Australian Government therefore needs to make a risk assessment of its protector’s availability in a climate-disrupted future or risk disappointment, as occurred when Britain proved unable to meet its Singapore Strategy guarantee in 1941. Whether the Australian population is ready to meet the cost of being a true sovereign people is yet to be seen, but its willingness to do so will be critical to the nation’s future security.

Conclusion

This article has painted a bleak future in which the resort to war is common and outcomes are decisive. There are many scientists, engineers and policy experts working on mitigating the worst of climate change. High-level policy experts, including the Reserve Bank of Australia^[39] and the Centre for Policy Development,^[40] continue to issue warnings of what is to come. International representatives continue to meet, as they did in Dubai in 2023, striving to find a way to reduce greenhouse gas emissions. Hopefully these efforts will succeed in preventing the worst predictions of climate change from becoming a reality, although nothing humanity does now will be able to prevent some of the consequences outlined here. Indeed, as one author has presciently observed, ‘The End of our World Order is Imminent’.^[41] A new future is coming, one that we will have to confront and adapt to if Australians are to survive as a people. Let us trust that the ADF and the nation are up to the task.

About the Author

Dr. Albert Palazzo is an Adjunct Professor at University of New South Wales –Canberra in the School of Humanities and Social Sciences. He was formerly the long-serving Director of War Studies for the Australian Army. He has written more than twenty books and monographs on the art of war, including The Australian Army: A History of its Organisation, 1901–2001, The Australian Army and the War in Iraq, The Battle of Crete, and From Moltke to Bin Laden: The Relevance of Doctrine in the Contemporary Military Environment and Climate Change and National Security: The Implications for the Military. He is currently writing a book that examines what is wrong with Australia’s defence policy and explains how to fix it.

Endnotes